Revert the change to the recaptcha import test.
Review Request #5776 — Created May 6, 2014 and submitted
For some mysterious reason, recaptcha doesn't always work with imp.find_module(). It works fine in my virtualenv, but not in Christian's, despite everything looking very similar. This changes our test back to using 'import', and crucially adds a comment explaining why we use that over imp.find_module().
